Summary

The goal is to implement an advanced Order 1 distance such that interclusters links are filtered according to their absolute weight.

Where

The function to add is in Gargantext > Core > Viz > Graph > Bridgeness.hs It is a variant of filterComs :

---- This function implemented in Order 1 graph distance, to be renamed something like 'O1 simple' takes the same number of links for each clusters pairs. ---------

filterComs :: (Ord n1, Eq n2)
           => Int
           -> Map (n2, n2) [(a3, n1)]
           -> Map (n2, n2) [(a3, n1)]
filterComs b m = Map.filter (\n -> length n > 0) $ mapWithKey filter' m
  where
    filter' (c1,c2) a
      | c1 == c2  = a
      -- TODO use n here
      | otherwise = take (b * 2*n) $ List.sortOn (Down . snd) a
           where
            n :: Int
            n = round $ 100 * a' / t
            a'= fromIntegral $ length a
            t :: Double
            t = fromIntegral $ length $ List.concat $ elems m

The alternative function, filterComs', let's call it for now 'Order1 Advanced', filter all inter-cluster links below a threshold. This threshold should ideally be a parameter at generation:

-- Weak links are often due to noise in the data and decrease the readability of the graph. 
-- This function prunes the links between the clusters when their weight is under a given 'threshold'.  
filterComs' :: (Ord a1, Fractional a1, Eq a2) =>
                     Int -> Map (a2, a2) [(a3, a1)] -> Map (a2, a2) [(a3, a1)]
filterComs' _b m = Map.filter (\n -> length n > 0) $ mapWithKey filter' m
  where
    threshold=0.03 -- this threshold will be moved to user parameters
    filter' (c1,c2) xs
      | c1 == c2  = xs
      | otherwise = List.filter (\(_nn,v) -> v >= threshold) xs

The goal of this issue is to create a new choice in the Graph distance drop down:

such that users can choose either simple O1 maps that highlights clusters or advanced O1 maps that enable to explore the relations between clusters.